Exploring the physiological determinants of marathon performance

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): ESPA 2014-2020

Background/Introduction: Long-time endurance exercise training leads to cardiovascular, respiratory, haematological and neuromuscular adaptations. The relative contribution of these adaptations to running performance in long-distance races remains to be elucidated in an integrative manner.

Purpose

The study of the relationship of marathon performance with anthropometric, cardiorespiratory and haematological adaptations.

Methods

Thirty-one marathon runners (26 males, age: 42 ± 9 years) were examined within 3 weeks before Athens marathon race (42.195 km). Assessment of training characteristics, anthropometric measurements, including height, body weight and body fat percentage, echocardiographic study, cardiopulmonary exercise testing using treadmill ergometer and blood test were performed.

Results

Training age was 11(1-39) years. Body fat percentage(BFP) was 17.3 ± 7.1% and body weight-indexed maximum oxygen uptake(VO2max) was 52.6 ± 8.9 mL/kg/min. Marathon race time(MRT) was 3:59:01(2:47:17-5:31:32). Among anthropometric measurements, MRT was positively associated with BFP(r= 0.561, p = 0.002) and body fat mass(r = 0.514, p = 0.005), even after adjustment for VO2max or oxygen uptake at first(VO2-VT1) or second(VO2-VT2) ventilatory threshold, implying an effect of BFP on running economy. Among echocardiographic parameters, MRT correlated negatively with right ventricular end-diastolic area(RVEDA) (r = -0.707, p < 0.001) and ratio of early to late diastolic transtricuspid flow velocity(TVE/A) (r= -0.430, p = 0.025). MRT correlated negatively with body weight-indexed VO2max (r= -0.692, p < 0.001), VO2-VT1 (r= -0.426, p = 0.019) and VO2-VT2 (r= -0.688, p < 0.001). MRT correlated negatively with maximum minute ventilation(VEmax) (r= -0.418, p = 0.022), VEmax indexed for body surface area(BSA) (r= -0.456, p= 0.011), maximum tidal volume(Vtmax) indexed for BSA(r= -0.436, p = 0.018) and oxygen uptake efficiency slope(OUES) (r= -0.529, p = 0.003). MRT was not associated with haemoglobin concentration. RVEDA correlated positively with maximum oxygen pulse (r = 0.653, p = 0.001), which is an estimate of stroke volume during exercise, and OUES(r = 0.534, p = 0.009). After performing multivariate linear regression analysis with MRT as dependent variable and BFP(standardized β=0.495, p = 0.001), RVEDA(standardized β= -0.550, p = 0.001) and Vtmax indexed for BSA(standardized β= -0.110, p = 0.418) as independent variables, only BFP and RVEDA were significant independent predictors of MRT(adjusted R2 = 0.667, p < 0.001 for the model).

Conclusions

The results of the present study demonstrated that the main cardiorespiratory adaptation that could predict a better marathon performance was right ventricular dilatation, through the increase in stroke volume during exercise, whereas upregulation of tidal volume during exercise was found to be a weaker predictor. The principal anthropometric determinant of marathon performance appears to be body fat percentage, via the influence on running economy.

Abstract Figure 1

Impact of a 246 km ultra-marathon race on global and segmental longitudinal deformation of all cardiac chambers and on inter-chamber relationships

Background

It is well documented that prolonged intense exercise such as a marathon, transitorily alters cardiac function. However, the impact of ultra-endurance (UE) exercise on global and segmental longitudinal deformation of all cardiac chambers and on inter-chamber functional relationships has not yet been thoroughly investigated.

Purpose

The aim of the study was the evaluation of the acute effects of UE exercise on longitudinal deformation of all cardiac chambers and on intra-, inter- and atrioventricular functional relationships.

Methods

Echocardiographic assessment was performed the day before and at the finish line of “Spartathlon”: a 246 Km ultra-marathon. 2D speckle-tracking echocardiography was performed in all 4 chambers during the same cardiac cycle, allowing a simultaneous strain-time data display of all cardiac chambers (Figure 1). Peak global deformation values and temporal parameters adjusted for the heart rate were extracted from the derived curves, while a segmental analysis for left (LV) and right ventricle (RV) was also performed.

Results

Out of 60 participants initially screened, 27 athletes (17 male, age 45±7 years) finished the race in 33:34±1:59 hours. Both LV (−20.9±2.3 pre- to −18.8±2% post-, p=0.009) and RV global strains (−22.9±3.6 pre- to −21.2±3% post-, p=0.04) decreased post-race, even though remained within normal range for the 85% of the participants. Peak atrial strains [right (RA) and left (LA)] did not change (p=0.12 and 0.95). Basal and mid segmental strain values significantly decreased post-race, while both LV and RV apical strain values remained unaffected (p=0.899 and p=0.46, accordingly) (Figure). Concerning interchamber relationships, RV and RA strain curves were constantly larger in magnitude than those of the LV and LA, with RV/LV, LV/LA, RV/RA and RA/LA peak values' ratios remaining unchanged from pre- to post-race. Finally, although right chambers' time-to-peak values were shorter compared to the left ones, all chambers' strain curves peaked later post-race (p<0.001 for all).

Conclusions

Despite subtle changes in LV and RV strain, 4-chamber deformation values remained within normal range even after running a 246 km ultra-marathon. Following a segmental analysis, this finding could be explained for both ventricles by a preservation of apical deformation. Additionally, inter- and atrioventricular concordance was also maintained.

Figure 1

Funding Acknowledgement

Type of funding source: None

Combination of novel and traditional cardiorespiratory indices for the evaluation of adolescent volleyball players

BACKGROUND

Although cardiopulmonary exercise (CPX) test is an essential tool for the assessment of functional capacity in athletes, limited information exists regarding the cardiorespiratory efficiency in young elite volleyball players. The main objective of the present study was to determine the maximal oxygen uptake (VO₂max) and ventilatory anaerobic threshold (VT) during the CPX test in young male and female volleyball players. Moreover, to describe the behavior of the novel cardiorespiratory optimal point (COP) index and to assess its association with VO₂max and VT.

METHODS

Eleven adolescent male (15.18 ± 0.75 years old) and 13 female (14.77 ± 0.44 years old) volleyball players underwent a graded maximal exercise test on a treadmill until exhaustion in order to obtain VO₂max, VT and COP. The COP was set as the lowest ventilation (VE)/VO₂ ratio at a given minute of spiroergometry.

RESULTS

COP values did not differ significantly between the two sexes (19.81 ± 1.29 and 20.44 ± 2.63 in males and females, respectively) and it was achieved at a speed of 3.41 ± 0.89 km/hr in males, and 3.78 ± 0.76 km/hr in females, lower than that achieved at the VT. COP was not correlated with VO₂max (56.32 ± 6.36 ml/kg/min and 44.78 ± 3.65 ml/kg/min) nor with VT (34.81 ± 10.13 ml/kg/min and 34.13 ± 5.87 ml/kg/min) in male and female young volleyball players, respectively.

CONCLUSIONS

The novel submaximal cardiorespiratory index of COP does not seem to be associated with the traditional aerobic capacity indices in athletes such as VO₂max and VT. Thus, it probably constitutes a separate parameter that needs to be further evaluated regarding its significance both in clinical evaluation and sports performance assessment of athletes. HIPPOKRATIA 2019, 23(2): 70-74.

Exploring the impact of sleep and stress on daily physical activity of cardiac patients: a preliminary study

BACKGROUND

Current approaches to cardiac rehabilitation services tailoring are often based on patient demographics or readiness for behavior change. However, the success of interventions acceptance and improved adherence to recommendations could be much higher when considering and adapting to a patient's lifestyle, such as sleep and stress.

AIMS

We aimed to analyze the potential associations between patient sleep and stress and daily moderate-intensity activity in patients with cardiovascular disease and to gain experience on the methods to collect and analyze a combination of qualitative and quantitative data.

METHODS

Patients with cardiovascular disease enrolled for an outpatient cardiac rehabilitation program were assessed at the study baseline regarding sociodemographic, clinical profile, and perceived level of stress. To collect daily physical activity and sleep data, all participants had two-week long diaries. Collected data was analyzed through correlation analysis, linear regression, and one-way ANOVA analysis.

RESULTS

The mean age of the participants (n =11) was 67.3 ± 9.6 years old. The patients were mainly male (82 %), married (91 %), and having at least one comorbid disease (64 %). The results of the analysis revealed that the night sleep duration is associated with moderate-intensity physical activity [F(1,6) =7.417, p =0.034]. Stress was not associated with patients' moderate-intensity daily physical activity.

CONCLUSION

The outcomes of the study can support the development of e-health and home-based interventions design and strategies to promote adherence to physical activity. Tailoring an intervention to a daily behavioral pattern of a patient, such as sleep, can support the planning of the physical activity in a form to be easier accepted by the patient. This finding emphasizes the need for further investigation of the association with a larger population sample and the use of objective physical activity and sleep-related measure instruments. HIPPOKRATIA 2019, 23(1): 15-20.

Effects of exercise training with traditional dancing on functional capacity and quality of life in patients with schizophrenia: a randomized controlled study

OBJECTIVE

To examine the effects of an eight-month exercise training programme with Greek traditional dancing on functional capacity and quality of life in patients with schizophrenia.

DESIGN

Randomized controlled trial.

SETTING

Sports Medicine Laboratory.

SUBJECTS

A total of 31 patients, aged 59.9 ± 14.1 years.

INTERVENTIONS

They were randomly assigned either to a Greek traditional dancing programme (Group A) or to a sedentary control group (Group B).

MAIN MEASURES

A functional capacity assessment was performed at baseline and the end of the study. Global Assessment of Functioning Scale and Positive and Negative Syndrome Scale were also used. Quality of life was examined using the Quality of Life and Satisfaction questionnaire.

RESULTS

After the eight months, Group A increased walking distance in the 6-minute walk test (328.4 ± 35.9 vs. 238.0 ± 47.6 m), sit-to-stand test (19.1 ± 1.8 vs. 25.1 ± 1.4 seconds), Berg Balance Scale score (53.1 ± 2.1 vs. 43.2 ± 6.7), lower limbs maximal isometric force (77.7 ± 25.7 vs. 51.0 ± 29.8 lb), Positive and Negative Syndrome Scale total score (77.0 ± 23.1 vs. 82.0 ± 24.4), Global Assessment of Functioning Scale total score (51.3 ± 15.5 vs. 47.7 ± 13.3) and Quality of Life total score (34.9 ± 5.2 vs. 28 ± 4.5), compared with Group B.

CONCLUSIONS

Our results demonstrate that Greek traditional dances improve functional capacity and quality of life in patients with schizophrenia.

Indirect estimation of VO2max in athletes by ACSM's equation: valid or not?

AIM

The purpose of this study was to assess the indirect calculation of VO2max using ACSM's equation for Bruce protocol in athletes of different sports and to compare with the directly measured; secondly to develop regression models predicting VO2 max in athletes.

METHODS

Fifty five male athletes of national and international level (mean age 28.3 ± 5.6 yrs) performed graded exercise test with direct measurement of VO2 through ergospirometric device. Moreover, 3 equations were used for the indirect calculation of VO2max: a) VO2max= (0.2 · Speed) + (0.9 · Speed · Grade) + 3.5 (ACSM running equation), b) regression analysis model using enter method and c) stepwise method based on the measured data of VO2. Age, BMI, speed, grade and exercise time were used as independent variables.

RESULTS

Regression analysis using enter method yielded the equation (R=.64, standard error of estimation [SEE] = 6.11): VO2max (ml·kg(-1)·min(-1)) = 58.443 - (0.215 · age) - (0.632 · BMI) - (68.639 · grade) + (1.579 · time) while stepwise method (R = .61, SEE = 6.18) led to: VO2max (ml·kg(-1)·min(-1)) = 33.971 - (0.291 · age) + (1.481 · time). The calculated values of VO2max from these regression models did not differ significantly from the measured VO2max (p>.05). On the contrary, VO2max calculated from the ACSM's running equation was significantly higher from the actually measured value by 14.6% (p <.05).

CONCLUSIONS

In conclusion, it seems that ACSM's equation is not capable of accurately predicting VO2max in athletes aged 18-37 years using Bruce protocol. Only the regression models were correlated moderately with the actually measured values of VO2max.

Importance of characteristics and modalities of physical activity and exercise in defining the benefits to cardiovascular health within the general population: recommendations from the EACPR (Part I)

Over the last decades, more and more evidence is accumulated that physical activity (PA) and exercise interventions are essential components in primary and secondary prevention for cardiovascular disease. However, it is less clear whether and which type of PA and exercise intervention (aerobic exercise, dynamic resistive exercise, or both) or characteristic of exercise (frequency, intensity, time or duration, and volume) would yield more benefit in achieving cardiovascular health. The present paper, as the first of a series of three, will make specific recommendations on the importance of these characteristics for cardiovascular health in the population at large. The guidance offered in this series of papers is aimed at medical doctors, health practitioners, kinesiologists, physiotherapists and exercise physiologists, politicians, public health policy makers, and the individual member of the public. Based on previous and the current literature, recommendations from the European Association on Cardiovascular Prevention and Rehabilitation are formulated regarding type, volume, and intensity of PA and exercise.

Brain natriuretic peptide and the athlete's heart: a pilot study

BACKGROUND

The role of brain natriuretic peptide (BNP) in differentiating the athlete's heart from maladaptive cardiac hypertrophy is unclear.

METHODS

To address this issue, an integrated M mode, two-dimensional B mode and Doppler echocardiographical study were performed and plasma BNP levels were measured in 25 strength athletes, 25 patients with established hypertrophic cardiomyopathy (HCM) and 25 healthy volunteers.

RESULTS

Among athletes, BNP levels correlated negatively with the total training time (r = -0.79, p = 0.002) and positively with ejection fraction (r = 0.58, p = 0.049) and fractional shortening (r = 0.57, p = 0.049). A BNP cut-off value of 11.8 pg/ml had 88% specificity and 74% negative predictive value for the exclusion of HCM.

CONCLUSIONS

Brain natriuretic peptide might be useful as a preparticipation screening test in athletes.

Heart rate variability modifications following exercise training in type 2 diabetic patients with definite cardiac autonomic neuropathy

OBJECTIVES

Cardiac autonomic neuropathy (CAN) as a result of diabetic autonomic neuropathy is positively related to a poor prognosis in diabetic patients. The measurement of heart rate variability (HRV) is a remarkable index of cardiac autonomic dysfunction. The aim of this study was to examine the effects of long-term exercise training on HRV in type 2 diabetic patients with definite CAN.

METHODS

Seventeen type 2 diabetic patients with definite CAN (group A: 56.2 years (SD 5.8)) and 15 without CAN (group B: 55.8 years (SD 5.6)) participated in the study. All patients followed an aerobic exercise training programme three times a week for 6 months; the intensity of the session was 70% to 85% of heart rate reserve. At the beginning and end of the study all subjects underwent graded maximal exercise testing with spiroergometry for the evaluation of their aerobic capacity (VO(2)peak). Moreover, time and frequency domain indices of HRV were obtained from 24 h ambulatory continuous ECG Holter recordings.

RESULTS

At baseline, all measurements of HRV indices were significantly reduced in group A compared with group B (p<0.05). Moreover, group A reached a significantly lower VO(2)peak by 14.8% compared with group B (p<0.05). Following the exercise training programme, the SD of all normal-to-normal RR intervals in the entire recording (SDNN) was increased by 18.8% (p<0.05) and 13.8% (p<0.05), the square root of the average of sum of squares of difference between adjacent filtered RR intervals (rMSSd) was increased by 35% (p<0.05) and 15.2% (p<0.05), and the percentage of differences between adjacent filtered RR intervals which was greater than 50 ms for the entire analysis (pNN50) was increased by 400% (p<0.05) and 67.9% (p<0.05) in groups A and B, respectively. Regarding the frequency domain indices, only the high frequency power (HF) was found to be significantly increased in group A. At the end of the exercise training programme, SDNN, rMSSd and low frequency power (LF) were significantly lower (24.3% (p<0.05), 20.3% (p<0.05) and 40% (p<0.05), respectively) in group A compared with group B. Also, VO(2)peak increased by 17.8% (p<0.05) in group A and by 11% (p<0.05) in group B. Furthermore, the exercise training programme had significant effects on blood lipid and glucose levels and glycosylated haemoglobin (HbA(1c)) in both groups.

CONCLUSIONS

The results indicate that 6-month aerobic exercise training improves the cardiac autonomic nervous system function in type 2 diabetic patients. However, more favourable effects are found in type 2 diabetic patients with definite CAN.

Cardiac function after exhaustive open-sea swimming

AIM

The present study examined the acute effects of exhaustive 25-km open-sea swimming on left ventricular (LV) function and morphology.

METHODS

Twenty elite male swimmers (22.3+/-4.1 years) participated in this study. Two-dimensionally guided M-mode echocardiograms, and electrocardiographic, phonocardiographic and carotid pulse tracings were performed simultaneously before and immediately after prolonged exhaustive swimming to evaluate the LV function and morphology, and the cardiac sympathetic outflow. Blood samples were also collected before and after the race to determine the hematocrit and the plasma concentrations of K+, Na+, Ca2+, a-ANP, renin, myoglobulin, CPK-MB, and lactate.

RESULTS

Exhaustive swimming was associated with a significant reduction in LV fractional shortening (-13%), ejection fraction (-11%), stroke volume (-25%), and LV internal diastolic diameter (-7%). In contrast, cardiac index was increased by 31%, total peripheral resistance was increased by 7%, and LV circumferential and meridional wall stresses were increased by 101% and 102%, respectively. Significant relationships were found between the increases in total peripheral resistance and LV circumferential wall stress and the decrease in ejection fraction. On the contrast, no significant relationship was found between the increased hematocrit and decreased ejection fraction. Furthermore, the pre-ejection period increased by 11%, the pre-ejection period to LV ejection time ratio increased by 15%, and the electrical to electromechanical systole relationship increased from -8 to 10 ms. Immediately after the race, there were significant increases in hematocrit (9%), and plasma concentrations of a-ANP (211%), renin (161%) and lactate (72%), myoglobulin (421%), and CPK-MB (141%) compared to pre-race values.

CONCLUSIONS

In elite athletes, prolonged exhaustive swimming is associated with depressed LV function, as suggested by reduced stroke volume, ejection fraction, and LV fractional shortening. This alteration is mainly due to increased afterload.

Health-related quality of life in end-stage renal disease patients: the effects of renal rehabilitation

Health-related quality of life (HRQoL) consists of a number of components like functional status, psychological and social functioning, cognition and disease and treatment-related symptoms. End-stage renal disease (ESRD) patients display emotional disturbances, as well as non-adherence to treatment and fluid and food intake, depression, anxiety, social withdrawal and cardiovascular and other co-existing disease morbidity. They have very low functional capacity and physical limitations in their daily activities that affect their mortality and morbidity. Exercise training in ESRD patients is effective in increasing work related activities and important components of their daily life and improving physical functioning. A physical rehabilitation program also leads to a reduction in depression and improvement in family and social interactions. Therefore, renal rehabilitation should be considered as an important therapeutic method for improving physical fitness, social function, well-being and thus health-adjusted quality of life in ESRD patients.

Outcomes of long-term exercise training in dialysis patients: comparison of two training programs

BACKGROUND

Exercise training has been shown to improve the low functional capacity and quality of life in dialysis (HD) patients. However, there are no data about the outcome of long-term exercise training and, also, the adherence of HD patients in such long-term renal rehabilitation programs. Therefore, the aim of this study was to evaluate the effects of 2 modes of long-term physical training on HD patients' physical fitness, perception of health and overall life situation.

PATIENTS AND METHODS

Forty-eight HD patients, free of any other systemic disease, who followed 2 modes of exercise training for 4 years, were studied. Half of them (group A) were randomly assigned to participate in a supervised outpatient exercise training program (3/weekly) on the non-dialysis days, while the other half (group B) followed a training program with stationary bicycles during their HD sessions (3/weekly). The measured domains of physical fitness and well-being every year were: aerobic capacity, as estimated from a modified Bruce treadmill exercise test and spiroergometric study, the patients' perception of health, the overall life situation and the employment status.

RESULTS

During the 4-year study, there were 8 drop-outs in group A and 5 in B. No adverse effects of the exercise programs were reported. The 1 year of exercise training resulted in 38% in group A (16 patients, who remained in the study) and 31% in group B (18 patients) improvement of exercise time, and a 47% increase in group A of peak oxygen consumption (VO2peak) and a 36% in group B in comparison to baseline value. After 3 additional years of training, significant improvements were also noted in exercise time (by 53% in group A and by 43% in B) and VO2peak (by 70% in group A and by 50% in group B), as well as in other gas exchange variables in comparison to baseline values. However, the improvements in group A were more pronounced than in B. Interestingly, the gains in exercise capacity were more enhanced in the first year of training in both groups. After 4-year training, significantly more patients in both groups perceived their health and overall life situation as well, compared to baseline. In addition, perception of improved health was higher in group A. The increase in the proportion of patients working was also higher in group A than B after the 4-year training.

CONCLUSION

HD patients can adhere to long-term physical training programs on the non-dialysis days, as well as during hemodialysis with considerable improvements in physical fitness and health. Although training out of HD seems to result in better outcomes, the drop out rate was higher.

Effects of athletic training on heart rate variability triangular index

The purpose of this study was to assess the heart rate variability triangular index (HRVI) in elite track and field athletes. Sixty healthy males (mean aged 22.1 +/- 3.5 years) -15 long distance runners (group A), 15 speed runners (Group B), 15 throwers (Group C) and 15 non-trained subjects (Group D) were submitted to spiroergometric test, m-mode echocardiography and 24-h ambulatory ECG monitoring. The HRVI, mean heart rate, mean interval between two consecutive R waves of the QRS complexes (R-R interval) and standard deviation of the R-R (SDRR) were assessed through time domain method on computed 24-h Holter recordings. The HRVI and the SDRR were 62.2 +/- 9.6 and 220 +/- 40 ms correspondingly in group A, 52.7 +/- 6.0 and 210 +/- 40 ms in B, 44.5 +/- 5.3 and 180 +/- 40 ms in C, 39.3 +/- 6.4 and 180 +/- 30 ms in D. The HRVI and the mean R-R were found to differ statistically between groups A, B and C versus D (P < 0.05). However, the higher value in HRVI was found in group A. Maximal oxygen consumption (VO2max) was 62.0 +/- 4.4 ml kg-1 min-1 in group A, 52.7 +/- 6.0 in group B, 44.6 +/- 5.3 in C and 41.6 +/- 6.0 in D. The higher value in VO2max was also found in group A. The left ventricular mass index (LVMI) and end-diastolic volume index (EDVI) were 136 g m-2 and 83 ml m-2 correspondingly in group A, 136 and 79 in B, 124 and 56 in C and 88 and 55 in group D. The HRVI was found to have a significant relationship with VO2max and EDVI only in group A. On the other hand, no significant relationships were found between HRVI and LVMI in all groups. It is concluded, that the enhanced HRVI in athletes is affected by exercise training pattern. Moreover, HRVI depends on the level of VO2max in endurance-trained, but is independent from the extent of myocardial hypertrophy in all types of training.

Cardiac effects of exercise rehabilitation in hemodialysis patients

Exercise training has well documented beneficial effects in a variety of cardiac disorders. End stage renal disease patients present many cardiovascular complications and suffer from impaired exercise capacity. No study to date has adequately examined the cardiac responses to exercise training in renal patients on hemodialysis (HD). To determine the effects of an exercise rehabilitation program on the left ventricular function at rest and during submaximal effort, 38 end-stage renal disease patients on maintenance HD were randomised into three groups. Sixteen of them (group A--mean age 46.4+/-13.9 years), without clinical features of heart failure, participated in a 6-month supervised exercise renal rehabilitation program consisting of three weekly sessions of aerobic training, 10 (group B--mean age 51.4+/-12.5 years) followed a moderate exercise program at home, and the other 12 (group C--mean age 50.2+/-7.9 years) were not trained and remained as controls. The level of anemia and the HD prescription remained constant during the study. Fifteen sex- and age-matched sedentary individuals (group D--mean age 46.9+/-6.4 years) were the healthy controls. All subjects at the start and end of the program underwent physical examination, laboratory tests, treadmill exercise testing, M-mode and 2-D echocardiograms performed at rest and at peak of supine bicycle exercise. Left ventricular volumes (EDV, ESV) and mass (LVM) were measured and ejection fraction (EF), stroke volume index (SVI) and cardiac output index (COI) were calculated by standard formulae. The maximal oxygen consumption increased by 43% (P<0.001) and the exercise time by 33% (P<0.001) after training in group A, by 17% (P<0.001) and 14% (P<0.01), respectively, in B, and both remained unchanged in group C. Training in group A was also associated with an increase in LVIDd (from 52.1+/-6.4 to 54.0+/-6.1 mm, P<0.001) and LVM (226+/-67 to 240+/-84 g, P<0.05) at rest with no change noted in groups B and C. Following a 6-month exercise training in group A an increase was also found in the resting EF by 5% (P<0.01) and SVI by 14% (P<0.001). There was no change found in groups B and C. Supine bicycle exercise after training in group A was associated with an improvement in EF by 14% compared to the pre-training change (P<0.001), SVI by 14% (P<0.001) and COI by 73% (P<0.001). These changes from rest to submaximal exercise were less pronounced in group B following training at home. The untrained patients demonstrated no changes in LV systolic function over the 6-month period. These results demonstrate that intense exercise training improves LV systolic function at rest in HD patients; both intense and moderate physical training leads to enhanced cardiac performance during supine submaximal exercise.

Effects of physical training on heart rate variability in patients on hemodialysis

Dysfunction of the cardiac autonomic nervous system is a known complication of end-stage renal disease. The objective of the study was to mainly investigate the effects of physical training on 24-hour vagal cardiac activity in dialysis patients. Sixty chronic uremic patients (mean age 48 +/- 12 years) on maintenance hemodialysis were studied. After initial evaluation, 30 patients (group A) were randomly assigned to a 6-month exercise training program (3/week). The other 30 patients (group B) and 30 nonuremic sedentary persons (group C) remained untrained and were used as controls. Parasympathetic activity was assessed at the beginning and the end of the study noninvasively from 24-hour electrocardiographic ambulatory monitoring by calculating heart rate variability (HRV). HRV index, mean NN interval, and standard deviation NN (SDNN) were measured according to the "triangular method." At baseline HRV index, mean RR, SDNN, and aerobic capacity were significantly reduced in both hemodialysis groups compared with values in group C. Also, 40% of all patients on hemodialysis and 16% of group C had arrhythmias (Lown class >II). Moreover, hemodialysis patients with a more depressed HRV index (<25, n = 37) had a higher incidence of arrhythmias (60%) compared to those with HRV index >25 (p <0.05). Exercise training in group A significantly increased HRV index from 22 +/- 7 to 28 +/- 9 (p <0.05) and SDNN from 0.11 +/- 0.03 to 0.13 +/- 0.04 (p <0.05). Furthermore, fewer patients continued to have an HRV index <25 (by 40%) and arrhythmias (by 33%) compared with baseline data. Training was also associated with a significant improvement in fitness level, as assessed by maximal oxygen consumption (by 41%; p <0.05) and exercise testing duration (by 33%; p <0.05). There was a significant correlation in HRV index and maximal oxygen consumption. No changes were observed in the control groups between baseline and follow-up data. Results demonstrate that physical training in hemodialysis patients augments cardiac vagal activity and decreases vulnerability to arrhythmias.

White coat hypertension detected during screening of male adolescent athletes

We investigated the utility of the selective use of ambulatory BP monitoring (ABPM) and echocardiography in detecting truly hypertensive adolescents from a cohort of young adolescent athletes undergoing BP screening. A total of 410 athletes (aged 16.4+/-2.6 years) were screened and, if initial BP measurement detected a persistently elevated BP (>140 mm Hg systolic or >90 mm Hg diastolic), ABPM and echocardiography were performed. Eighteen clinically hypertensive cases (4.4%) were detected and evaluated with a 24-h ABPM. Sixteen of them were defined as having "white coat hypertension" because they were detected to have normal daytime and nocturnal BP. An elevated level of BP confirmed on ABPM was recorded in only two (0.5%) athletes. Echocardiography failed to demonstrate significant abnormalities.

The effects of exercise training on muscle atrophy in haemodialysis patients

BACKGROUND

Patients with end-stage renal disease on haemodialysis (HD) have limited work capacity. Many structural and functional alterations in skeletal muscles contribute to this disability.

METHODS

To evaluate the effects of exercise training on uraemic myopathy, seven HD patients (mean age 44.1+/-17.2 years) were studied. Open muscle biopsies were taken from their vastus lateralis muscle before and after a 6-month exercise rehabilitation programme and examined by routine light- and transmission electron-microscopy. Histochemical stainings of frozen sections were performed and morphometric analysis was also applied to estimate the proportion of each fibre type and the muscle fibre area. Spiroergometric and neurophysiological testing and peak extension forces of the lower limbs were measured before and after exercise training.

RESULTS

All patients showed impaired exercise capacity, which was associated with marked muscular atrophy (mean area 2548+/-463 microm2) and reduction in muscle strength and nerve conduction velocity. All types of fibres were atrophied, but type II were more affected. The ultrastructural study showed severe degenerative changes in skeletal muscle fibres, mitochondria, and capillaries. Exercise training had an impressive effect on muscular atrophy; in particular the proportion of type II fibres increased by 51% and mean muscle fibre area by 29%. Favourable changes were also seen on the structure and number of capillaries and mitochondria. These results were confirmed by a 48% increase in VO2 peak and a 29% in exercise time, as well as an improvement in the peak muscle strength of the lower limbs and in nerve conduction velocity.

CONCLUSIONS

Skeletal muscle atrophy in HD patients contribute to their poor exercise tolerance. The application of an exercise training rehabilitation programme improved muscle atrophy markedly, and therefore had beneficial effects in overall work performance.

Effect of exercise on the proportion of unsaturated fatty acids in serum of untrained middle aged individuals

OBJECTIVES

To examine whether prolonged moderate exercising by untrained middle aged individuals of both sexes affects the plasma ratio of unsaturated to saturated (U/S) fatty acids in the non-esterified fatty acid (NEFA) and triacylglycerol (TG) fractions.

METHODS

Twenty two healthy untrained volunteers (eleven men and eleven pre-menopausal women), aged 35-55, exercised on bicycles at 50-55% maximal heart rate reserve (estimated 61% maximal oxygen uptake) for one hour. Pre- and post-exercise blood samples were analysed for lactate, glucose, glycerol, individual NEFAs and TG acyl groups, cholesterol, high density lipoprotein cholesterol, urea, cortisol, and testosterone. Biopsy specimens of adipose tissue were analysed for TG acyl group composition.

RESULTS

Serum total NEFAs increased significantly whereas total TG decreased significantly in both sexes. Changes in individual fatty acids, in both the NEFA and TG fractions, generally paralleled changes in the total pool but were not proportionate. As a result, U/S NEFAs increased in both sexes, although significantly only in women. The shift was in the direction of the composition of the major source of blood NEFAs--that is, adipose tissue TG. U/S acyl groups of TG also increased in both sexes, although significantly only in men.

CONCLUSIONS

Prolonged moderate exercise increases the U/S ratio of serum NEFAs and TG. This may add to the beneficial effects of exercise given the protective role of unsaturated fatty acids against coronary heart disease.

Exercise renal rehabilitation program: psychosocial effects

The aim of this study was to assess the psychosocial effects of exercise training on hemodialysis (HD) patients. Thirty-one uremic patients, aged 50.6+/-11.6 years, on maintenance HD were studied. Twenty patients were selected at random for a 6-month exercise renal rehabilitation program (ERRP) consisting of 3 weekly sessions of exercise training. The other 11 patients were assigned to sedentary control status. A formal psychosocial assessment, which included affective (Beck Depression Inventory, BDI), quality of life (Quality of Life Index, QLI) and personality (Eysenck Personality Questionnaire, EPQ) parameters, was performed with validated questionnaires at the beginning and the end of the ERRP. After training significant improvement occurred in physical capacity (VO2max increased from 16.8+/-6.2 to 23.2+/-7.6 ml/kg/min, p < 0.05). Although the level of depression did not differ betwen the 2 groups at pretesting, the ERRP group showed a decrease in their self-report of depression (decrease in BDI score value, from 21.0+/-10.4 to 13.7+/-9.5, p < 0.05) after the training program. From the relationship between the baseline levels of BDI depression and changes in VO2max in the ERRP group it was suggested that the most severely depressed patients got the greatest beneficial effects from exercise training. Moreover, trained patients demonstrated an improvement in QLI (from 6.3+/-1.5 to 9.0+/-0.9, p < 0.05). This improvement was found to be dependent on the participation in ERRP, the effects of the training and the improvement in the depression. All the above functional and psychosocial parameters remained unchanged in the controls. The results demonstrate that ERRP is an effective emotional therapeutic method for HD patients and improves their quality of life.

Plasma TSH, T3, T4 and cortisol responses to swimming at varying water temperatures

The acute effect of 30-min swimming at a moderate speed, at three water temperatures (20, 26 and 32 degrees C) on plasma thyroid stimulating hormone (TSH), free thyroxine (F.T4), triiodothyronine (T3) and cortisol concentrations was studied in 15 élite male swimmers. Blood was sampled before and immediately after the events. The heart rate, which was continuously monitored during exercise, had the highest response at 32 degrees C and the lowest at 20 degrees C. Blood lactate concentrations were found to be similar after the three tests. Plasma TSH and F.T4 were found to be significantly increased (by 90.4% and 45.7% respectively) after swimming at 20 degrees C, decreased at 32 degrees C (by 22.3% and 10.1% respectively) and unchanged at 26 degrees C. Exercise at these three water temperatures did not significantly affect T3. Finally, plasma cortisol was found to be increased after swimming at 32 degrees C (by 82.8%) and 26 degrees C (by 46.9%), but decreased at 20 degrees C (by 6.1%).